Re: [RFC 11/33] KVM: x86: hyper-v: Handle GET/SET_VP_REGISTER hcall in user-space

[Alexander Graf]

On 08.11.23 12:17, Nicolas Saenz Julienne wrote:

Let user-space handle HVCALL_GET_VP_REGISTERS and
HVCALL_SET_VP_REGISTERS through the KVM_EXIT_HYPERV_HVCALL exit reason.
Additionally, expose the cpuid bit.

Signed-off-by: Nicolas Saenz Julienne <nsa...@amazon.com>
---
  arch/x86/kvm/hyperv.c             | 9 +++++++++
  include/asm-generic/hyperv-tlfs.h | 1 +
  2 files changed, 10 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index caaa859932c5..a3970d52eef1 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2456,6 +2456,9 @@ static void kvm_hv_write_xmm(struct kvm_hyperv_xmm_reg 
*xmm)

static bool kvm_hv_is_xmm_output_hcall(u16 code)

  {
+       if (code == HVCALL_GET_VP_REGISTERS)
+               return true;
+
        return false;
  }

@@ -2520,6 +2523,8 @@ static bool is_xmm_fast_hypercall(struct kvm_hv_hcall *hc)

        case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
        case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
        case HVCALL_SEND_IPI_EX:
+       case HVCALL_GET_VP_REGISTERS:
+       case HVCALL_SET_VP_REGISTERS:
                return true;
        }

@@ -2738,6 +2743,9 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)

                        break;
                }
                goto hypercall_userspace_exit;
+       case HVCALL_GET_VP_REGISTERS:
+       case HVCALL_SET_VP_REGISTERS:
+               goto hypercall_userspace_exit;
        default:
                ret = HV_STATUS_INVALID_HYPERCALL_CODE;
                break;
@@ -2903,6 +2911,7 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct 
kvm_cpuid2 *cpuid,
                        ent->ebx |= HV_POST_MESSAGES;
                        ent->ebx |= HV_SIGNAL_EVENTS;
                        ent->ebx |= HV_ENABLE_EXTENDED_HYPERCALLS;
+                       ent->ebx |= HV_ACCESS_VP_REGISTERS;

Do we need to guard this?


Alex




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